At present, both “environment protection and energy conservation” and “perfect harmony of human, vehicles and nature” have become common themes in the vehicle industry along with the increasingly severe phenomenon of global warming and the gradually grievous petroleum supply and demand contradiction.
A hybrid powered vehicle integrates reasonably motor drive with engine drive. The advantage of the motor drive is utilized to remedy the disadvantage of the engine drive, and the engine is kept operative in an optimal condition, thereby enabling such functions of the engine as Idle stop, drive assistance, regenerative brake energy recycling, etc. Thus, the hybrid powered vehicle improves the performance of steering the vehicle and saves the energy consumption thereof. And, the engine emission is lowered and the advantages of both the internal-combustion engine vehicle and the electrical vehicle are fully utilized. Therefore, the hybrid powered vehicle is a vehicle with low emission and low oil consumption and is the most worthy of a practical development at present.
Since the hybrid power system is a combination of the engine drive and the motor drive, the performance of controlling the motor drive strongly influences that of the hybrid power system. In order to achieve good smoothness of the entire vehicle using the hybrid power system, smoothing of a torque of a motor in the hybrid power is an essential factor in a system for controlling the motor in the hybrid power.
For smoothing of a torque of a motor in the prior art, typically a torque variation step is set by a motor control system to simply control the slope of a torque variation curve. This control method results in the continuous but unsmooth torque variation curve as illustrated in FIG. 4. Moreover, this control method results in a long response time in the case of a significantly varied torque demand, adversely influencing an acceleration demand for the entire vehicle using the motor control system. Therefore, it is very necessary to smooth reasonably and efficiently a torque of a motor in a hybrid power system.